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Positive Feedback ISSUE 55
may/june 2011


An Interview With Jack Wu of Woo Audio
by Bob Youman


woo amp

Bob Youman Since establishing a strong beachhead with several entry level and high-end audiophile headphone amplifiers, Woo Audio has continued to grow and roll out an impressive line of many new amplifier products. Their vision for the future of Woo Audio and this market is extremely aggressive and insightful. The following interview with Jack Wu is a supplement to my reviews of the Woo Audio WA22 and WES headphone amplifiers. Please see the Woo Audio web site for more specific model and pricing information.

My understanding is that Woo Audio is a family affair. Can you explain a little of the history of the company and the key players and their roles?

Jack Wu The company was formed in 2003. We are located in Queens, New York. Except for metal and casing work, all company business management functions, research and development and assembly are performed at this location.

There are many important employees and contributors to the success of our company, but the three key players are my father Wei Wu, my brother Zhidong Wu and myself. We three all wear several hats and there is some common and shared input for all functions, but we each have primary responsibilities.

My father is the chief engineer and designer from a technical perspective. He is self-taught but he has an impressive amount of technical knowledge and experience that spans over 40 years. He is an extreme DIYer and made his first television in his hometown in his earlier 20's.

As a young man in China, he was in charge of sound at the Cantonese Opera. This required expertise in both solid state and tube electronics. It also provided him with insight and experience with the sound of live music. This background has greatly impacted the design and manufacturing of our products. It is a key reason for our success.

woo amp

My brother is in charge of all manufacturing processes. He takes the input and direction from my overall product vision and my father's fundamental design and makes it a reality. His focus is on execution and quality. This is extremely difficult considering our high standards and the extensive range of components, costs and associated performance requirements.

My own responsibilities are primarily focused on pre-sales and post-sales support, purchasing, and quality control. This includes basic business management, marketing and customer support. Though we all contribute to the overall product design, I like to think of myself as the visionary for defining the scope and objectives for new products. This can be from both an aesthetic and performance perspective.

BY What generated this focus on headphone amplifiers?

JW Our family roots and experience are grounded in New York City (NYC). From the beginning, we felt that due to the size, cost and privacy concerns of a typical NYC apartment, it was difficult for a city dweller to find a way to implement and realize a high level of quality sound. So, it all started with a simple customer need (like most product ideas) and a focus on big city living requirements, but market demand has obviously grown well beyond that.

High-end headphones were readily available to the market. More and more models were being introduced and the quality of sound was getting better and better. We felt that there was a definite opportunity and need for better solutions to drive these high-end headphones—specifically with tube amplifiers. Thus Woo Audio.

Yes, our focus is on headphone amplifiers but let me remind you that we do manufacture products specifically designed for driving stand-alone speakers. This includes the WA5 amplifier and several monoblock designs. We also support a significant amount of custom work in this area. Our customers recognize the quality of performance and aesthetics that we have established with our headphone amplifiers. You would be amazed at some of the unique custom projects that we have supported with tremendous success. We are very open to our customers needs for both headphone and stand alone speaker applications.

BY What are the key design philosophies behind your product line? What differentiates you from your competition?

JW We are all about tubes, but it is much more than that. We have our own in house R&D team that we are very proud of. It is an important differentiator. We feel strongly that proper design and implementation is easier said than done. You must have the knowledge and experience for both the technical requirements and the electrical characteristics of specific tubes before including them in a design. Final design decisions are almost always a combination of science and art.

woo amp

We hold core technology as a key in designing and developing the most critical components. This includes the power supply transformers, inductors, and output transformers. These components are critical as they often translate to success or failure. Development costs and lifecycle are also greatly reduced because we don't have to rely on suppliers or their capabilities.

Though we test and measure all performance criteria, we listen objectively and extensively to our prototypes as we work through the design process. It is a tremendous challenge to stay knowledgeable on all the options available to reach certain performance goals. Again, even with this knowledge, proper implementation is the key. This is our value added and competitive advantage.

BY Performance is obviously the priority, but Woo Audio is also known for excellent aesthetics and build quality. Who in the company are the primary designers and drivers of these aesthetic decisions?

JW Thank you for that compliment. We are very proud that our products provide not only superior performance but also the highest quality build and aesthetic qualities. This is truly a team effort. For example, I may start the process with an overall aesthetic vision for a new product, but my brother and father are equal contributors. As I said, my brother is all about execution and quality—which can greatly influence the final look and build of the product. His CAD/CAM skills also play a major role. My father has considerable experience with casing and metal work design. We feel that aesthetics is another one of our key differentiators.

BY Any comments about the WES design and/or performance that you might want to highlight for our readers?

JW One important element of the WES design is it's tremendous ability to support wide voltage swings. Peak to peak, it can support swings of up to 1400 volts. Again, appropriate tube implementation is a key, but we also use special wound load inductors. While these inductors can greatly enhance EL34 performance, they pose a tremendous challenge in this design. These parts require low capacitance and proper inductance. We evaluated many winding methods and several different materials to get the desired results. This is unique to the WES, and it does provide additional transparency, detail and speed.

We are big believers in electrostatic headphones. They behave much like a simple capacitor when supported properly. They have the ability to provide improved dynamics, better frequency response, and a very realistic sound. The WES has an extremely robust power supply. The stackable two-unit design allowed us greater flexibility and improved performance.

BY Do you have any comments about the headphone industry and market in general? What new Woo Audio products will we see in the future?

JW We are very excited about the high-end headphone market (and associated products) as it continues to have respectable growth and sales opportunities. MP3 and hi-definition music will each play a major role. We expect to see a range of both economical and higher quality listening solutions. With that in mind, we have a long-term vision and commitment to an end-to-end Woo Audio headphone system.

woo amp

In a few months, our new DAC and CD Transport will be announced to the public. Probably in parallel, you will also see a new monoblock headphone/speaker amplifier. We are thrilled to introduce this new amplifier to our customers. It combines breakthrough innovation and much improved key components.

Finally, but not least, we plan on introducing a high-end headphone to the market. This has always been my dream and we are elated that this will soon be a reality!

Woo Audio